The present invention relates generally to a MEMS (Micro-Electro-Mechanical Systems) and more specifically to a control arrangement for a MEMS actuator which reduces charge errors and which allows more precise control of the MEMS actuator position and increases control range.
When a MOS (Metal Oxide Semiconductor) switch turns off, charge injection errors occur by way of two mechanisms. The first is due to channel charge, which must flow out from the channel region of the transistor to the drain and source junctions. The second charge is due to overlap capacitance between the gate and drain. These can induce drawbacks in MEMS devices wherein this charge can diminish the degree to which a gap in a device, such as variable capacitor, which is associated with the transistor and the control of the MEMS, can be accurately controlled. In the worst case, these effects can be sufficient to cause a capacitor to go into pull-in mode and undesirably snap down.
An arrangement which enables the charge injection into a MEMS variable capacitor to be diminished during MOS switch off is therefore necessary.